Thousands of US-backed fighters opened a major new front in Syria's war, launching an offensive to drive Islamic State out of a swathe of northern Syria it uses as a logistics base, and were reported on Wednesday to be making swift progress. The operation, which began on Tuesday after weeks of quiet preparations, aims to choke off the group's access to Syrian land along the Turkish border that the militants have long used to move foreign fighters back and forth to Europe.
"It's significant in that it's their last remaining funnel" to Europe, a US military official told Reuters. A small number of US special operations forces will support the push on the ground to capture the "Manbij pocket" of territory, acting as advisers and staying back from the front lines, the officials said, speaking on condition of anonymity to discuss military planning.
"They'll be as close as they need to be for the (Syrian fighters) to complete the operation. But they will not engage in direct combat," the official said. The operation will also count on airpower from the US-led coalition, which pounded Islamic State positions near Manbij with 18 strikes on Tuesday, including six militant tactical units, two headquarters facilities and a training base.
Driving Islamic State from its last remaining foothold at the Turkish border has been a top priority of the US-led campaign against the group. The group controls around 80 km (50 miles) of the frontier stretching west from Jarablus. Still, some US military and intelligence officers caution Islamic State has proved adaptable, willing to change tactics. In Iraq, for example, the Sunni extremist group has countered some territorial and other losses by staging attacks in Baghdad, the seat of the country's Shia-led government. The Syrian Observatory for Human Rights said US-led air strikes in support of the ground operation killed 15 civilians including three children near Manbij in the last 24 hours. The Observatory's reporting is based on an activist network in Syria. It said the Syria Democratic Forces (SDF) alliance, which is conducting the assault to capture the Manbij pocket, had taken 16 villages and was 15 km (9 miles) from Manbij town itself."